Assembly for the on-line flushing and filling of an extracorporeal blood circulation system of dialysis machines

ABSTRACT

A dialysis machine assembly having an internal flushing and filling facility for a blood flow circuit of the assembly is disclosed. The dialysis machine assembly includes dialyzer having a membrane and an inlet and an outlet for blood side with corresponding blood tubes and an inlet and an outlet for dialysate side with a valve located downstream of the outlet for dialysate side. A dialysis liquid supply is connected to the inlet for the dialysate side and the valve is partially closed to force dialysis liquid to flow through the membrane from the dialysate side to the blood side through the blood tubes to flush and fill a blood flow circuit prior to performing a dialysis treatment with the dialysis machine.

This is a divisional of application Ser. No. 07/892,792 filed on Jun. 1,1992, now U.S. Pat. No. 5,259,961.

BACKGROUND OF THE INVENTION

This invention relates to a method for flushing and filling anextracorporeal blood circulation system of dialysis machines, inparticular blood tubes and dialyzer, and to an assembly with the aid ofwhich an extracorporeal blood circulation system can be flushed andfilled. The filling process includes the deaerating of theextracorporeal blood circulation system, the deaerating operation beingan indispensable precondition for a dialysis treatment.

Disposable tubes which are normally packed under sterile conditions andhave to be flushed, deaerated and filled prior to a treatment arenowadays used a arterial and venous blood tubes of an extracorporealblood circulation system. These operations have so far been carried outwith physiological salines that are conveyed by the blood pump of themachine through the tub system and the dialyzer to flush theextracorporeal blood circulation system, thereby freeing it fromimpurities, and to fill the system, so that air is entirely removed.

The use of a saline flushing liquid has the disadvantage that it entailsconsiderable costs.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a method which isused for flushing, deaerating and filling an extracorporeal bloodcirculation system of dialysis machines and which is neverthelessinexpensive. It is another object to provide an assembly with which thismethod can be carried out.

In the method of the invention, the dialysis liquid which has beenproduced or prepared by the dialysis machine is conveyed through or intothe extracorporeal blood circulation system for the purpose of flushing,deaerating and filling. As a result, a saline solution filled into a bagneed no longer be provided for this purpose. Moreover, such a bag had tobe connected by an operator to the arterial blood tube in former times.Furthermore, saline solutions need no longer be kept available in greatamounts for such a purpose, and empty bags need no longer be disposedof.

In accordance with the invention, the dialysis liquid is taken at theblood side of the dialyzer and filtered thereby. This ensures agerm-free state of the flushing and filling liquid in a reliable way,with the dialysis liquid serving as an entirely acceptable substitutefor the saline solution.

According to another inventive suggestion, the dialysis liquid takenfrom the dialyzer can be pumped by the blood pump of the machine throughthe extracorporeal blood circulation system, which shall be explained inmore detail in the following. In this embodiment of the invention, thesuction side of the arterial blood tube is preferably connected by meansof a disposable article or connector to the dialyzer, preferably at thepoint to which the venous blood tube is connected during a dialysistreatment. The blood pump segment of the arterial blood tube is insertedinto the blood pump of the machine, preferably a roller-type pump, andthe other, free end of the arterial blood tube is preferably coupled viaanother disposable article with the inlet of the venous blood tube. Thevenous blood tube is passed across an air detector in the conventionalway. The other end of the venous blood tube is connected downstream ofthe dialyzer to the dialysis liquid circuit, preferably by means ofanother disposable article, to a sampling valve of this dialysis liquidcircuit.

When the blood pump is out into operation, dialysis liquid is drawnthrough the semipermeable membrane of the dialyzer into the blood tubes.Only sterile and germ-free flushing liquid flows into the extracorporealblood circulation system. The flushing liquid and the air previouslyexisting in the extracorporeal circuit are introduced downstream of thedialyzer machine, whereby disturbances of the equilibrium or othermachine faults are avoided.

According to an alternative suggestion of the invention, the dialysisfluid is pumped by a pump of the dialysis liquid circuit, and not t ythe blood pump of the machine, through or into the blood tubes for thepurpose of flushing, deaerating and filling the extracorporeal bloodcirculation system. This process may be initiated by the filling programof the machine.

To be more specific, in this embodiment of the method of the invention,the arterial and venous blood tubes are coupled to the dialyzer in thesame way as during a dialysis treatment. In the dialysis liquid circuit,a three-way valve with 2/2 ports is arranged downstream of the dialyzerfor closing the dialysis liquid circuit either fully or partly or forinterrupting the same. The third port of this three-way valve which may,e.g. be adjusted mechanically is not positioned in the dialysis liquidcircuit and is capable of establishing a connections which is open tothe atmosphere. The valve partially or entirely blocks return of thedialysis liquid through its own circuit and causes the liquid to passthrough the dialyzer and through the blood tubes.

In a preferred embodiment of the invention, the three-way valve is anelectrically operated valve which is controlled by the dialysisapparatus itself or by an additional device.

For flushing and filling the extracorporeal blood circulation system,the three-way valve is operated in such a way that the dialysis liquidcircuit is opened to the atmosphere, whilst the line leading away fromthe dialyzer is closed fully or partly. It should be noted that it isalso possible to adjust and intermediate position of the three-way valvein which only part of the dialysis liquid can flow off through the valveassembly. This shall be explained further below.

When the dialysis liquid circuit is open to the atmosphere die to theswitching of the three-way valve, the sensor means of the machine cansense the air flowing via the associated connection into the interior ofthe machine, and initiate the filling program specific to the machine.The dialysis liquid from the machine is pressed via the dialyzer intothe two connected blood tubes, since the three-way valve has interruptedthe dialysis liquid circuit either fully or partly. The blood tubes aretitus flushed, deaerated and filled with the dialysis liquid.

According to another inventive suggestion, the connections at thepatient are, e.g., coupled to an empty bag. In this case it might be ofadvantage to switch the three-way valve to an intermediate position atwhich the dialysis liquid circuit is closed only partly. As a result,the bag is not filled with an amount of flushing liquid that is toogreat, and is also not subjected to a pressure that is too great andmight make the bag burst.

In an alternative embodiment of the invention, the connections of thetwo blood tubes at the patient can be coupled to the third connection ofthe three-way valve which is not positioned within the dialysis liquidcircuit, i.e. preferably by means of a suitable disposable article.Another possibility is that the free ends of the blood tubes arearranged such that they terminate in an open vessel.

In this last-mentioned embodiment of the method of the invention and theassembly of the invention, respectively, the arterial pump segment isnot inserted into the blood pump because the arterial blood tube isfilled in the opposite direction.

An advantage of the above-described second variant is that steriledisposable articles are not needed at the dialyzer side and that thearterial and venous blood tubes are connected in the usual way and neednot be varied in any way.

The flushing and filling process need not necessarily be initiated bythe filling program specific to the machine, which program is responsiveto air flowing into the interior of the machine.

The assembly of the invention has already been described above to alarge extent in connection with the method of the invention. Accordingto an additional inventive suggestion, a sterile filter is arrangedupstream of the dialyzer in the dialysis liquid circuit to promote andensure the necessary germ-free state.

According to another aspect of the invention, the dialysis liquid whichis used as a flushing liquid is employed at the end of the dialysistreatment for flushing the extracorporeal blood circulation system. Forthe is purpose, it is expedient to discharge said liquid during theflushing operation into a bag. A flushing operation is necessary toreturn all of the blood to the patient after a dialysis treatment. Thishas so far been accomplished with the air of a saline solution.

According to another inventive suggestion, the extracorporeal componentsare cleaned such that they can be used again. To this end, an assemblymay be chosen as is described further above in connection with the firstembodiment of the method of the invention. During a cleaning programspecific to the dialysis machine, cleaning liquid is passed due to theconveying action of the blood pump via the semipermeable membrane of thedialyzer into the extracorporeal circuit, with the latter being therebycleaned.

It is, of course, within the scope of the invention to further se theextracorporeal components as disposable articles.

It will be understood that during dialysis treatment, the blood anddialysis liquid flow in separate paths on either side of the membrane ofthe dialyzer. During the flushing operation, dialysis liquid is filteredthrough the membrane and into the blood circulation components.

Other features, advantages and details of the invention will becomeapparent from the following description of some preferred embodimentstaken in conjunction with the drawing, in which there is shown in apurely diagrammatic way.

THE DRAWING

FIG. 1, a first embodiment of the assembly of the invention;

FIG. 2, a conventional assembly; and

FIG. 3, a second embodiment of the assembly of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First of all, reference is made to FIG. 2 to explain conventionalmethods employed for flushing, deaerating and filling an extracorporealblood circulation system. The figure illustrates a dialysis machine 1proper having an upper monitoring level 2, a central level 3 comprisinga blood pump 4 and an air detector 5, as well as a lower level 6including the hydraulic part.

Dialysis machine 1 is connected via a supply line 7 to dialyzer 8 fromwhich a return line 9 leads back to dialysis machine 1 to close adialysisliquid circuit.

An arterial blood tube 10 and a venous blood tube 11 are connected todialyzer 8 at the illustrated points for carrying out a dialysistreatment. A blood pump segment 12 of the arterial blood tube 10 isinserted into blood pump 4, whilst the venous blood tube 11 is guidedvia air detector 5.

For the preparation of a dialysis treatment, blood tubes 10 and 11 mustbe flushed and the extracorporeal blood circulation system must bedeaerated and filled. To this end, it has so far been customary toconnect the free end of the arterial blood tube 10 to the outlet of abag 13 containing a salt solution. Blood pump 4 conveys the saltsolution through the arterialblood tube 10, dialyzer 8, venous bloodtube 11 and air detector 5 to discharge the flushing liquid into an opencontainer 1,4 in the end.

Reference is now made to FIG. 1 in which, just like FIG. 3, thecomponents corresponding to those of FIG. 2 are designated by identicalreference numerals. For the sake of clarity, these reference numeralswill not be repeated.

In this embodiment of the invention, the arterial blood tube 10 isconnected by means of a disposable article 15 to dialyzer 8 at the placeto which the venous blood tube 11 is coupled a according to FIG. 2. Theblood pump segment 12 of the arterial blood tube 10 is inserted intobloodpump 4, and the free end of the tube 10 is connected by means of adisposable article 16 to the venous blood tube 11. The venous blood tube11, in turn, is guided across air detector 5 and is connected by meansof disposable article 17 to a sampling valve 18.

A sterile filter 19 which promotes and ensures the germ-free conditionof the flushing liquid is arranged in line 7 of the dialysis liquidcircuit.

Dialysis liquid is conveyed by blood pump 4 from the dialysis liquidcircuit 7, 8, 9 into the arterial tube 10 and the venous tube 11, fromwhere it is returned into the dialysis liquid circuit (at 18) to avoiddisturbances of the equilibrium or other machine faults.

In the embodiment of the invention illustrated in FIG. 3, the arterialblood tube 10 and the venous blood tube 11 are connected to dialyzer 8in the way as described with reference to FIG. 2 and require during adialysis treatment. In this embodiment, a three-way valve 20 is arrangedin line 9. Connections 21 and 22 of said valve are assigned to line 9,whilst its connection 23 is normally open to the atmosphere.

During a dialysis treatment a connection is established between 21 and22, whilst, as already stated, connection 23 is open to the atmosphere.For the purpose of flushing the extracorporeal blood circulation system,valveassembly 20 is switched to passage 22, 23. An intermediate positionin which there exists a restricted passage 21, 22 can also be selected.Dialysis liquid from dialysis machine 1 is pressed via dialyzer 8 intoblood tubes 10, 11, with the latter being flushed. Flushing liquid maybe discharged either via lines 24 into a bag 25 or via lines 26 into a aopenvessel 14 or may be supplied via lines 27 to connection 23 ofthree-way valve 20, from where liquid is passed into the dialysis liquidcircuit or rather line 9 thereof.

The blood pump segment is not inserted into blood pump 4 in thisembodiment.

I claim:
 1. A dialysis machine assembly having an internal flushing andfilling facility for a blood flow circuit of the assembly, said dialysismachine assembly comprising a dialyzer having a membrane, a first inletand a first outlet in said dialyzer on one side of the membrane, a firstblood tube connected to said first inlet and a second blood tubeconnected to said first outlet, a second inlet and a second outlet insaid dialyzer on the other side of the membrane, a dialysis liquidsupply means for providing dialdysis liquid under pressure into saidsecond inlet and through said second outlet and forming a dialysisliquid circuit, sterile filter means upstream of said second inlet forassuring a germ-free state of dialysis liquid entering said secondinlet, a valve means in said dialysis liquid circuit located downstreamof said second outlet, and means for at least partially closing saidvalve means and forcing dialysis liquid to flow through the membrane toprovide a sterile liquid passing out of said first inlet and outlet andthrough said first and second blood tubes to flush and fill the bloodflow circuit prior to performing a dialysis treatment with said dialysismachine.
 2. The assembly of claim 1 wherein said valve means comprises athree way valve having three connections, two of said connections beingin said dialysis liquid circuit.
 3. The assembly of claim 2 wherein oneof said connections is open to the atmosphere.
 4. The assembly of claim1 wherein said valve means is mechanically operable.
 5. The assembly ofclaim 1 wherein said valve means is electrically operable.
 6. Theassembly of claim 1 wherein said valve means is automaticallyadjustable.
 7. The assembly of claim 1 wherein said blood tubes haveoutlets and said outlets are connected to a container.
 8. The assemblyof claim 1 wherein said blood tubes have outlets, said valve meanscomprises a three way valve having three connections, two of saidconnections being in said dialysis liquid circuit, and the thirdconnection being to the outlets of said blood tubes.